1. Field of the Invention
The invention relates to a vehicle seat. More specifically, the invention relates to a vehicle seat that includes a seat frame made of metal.
2. Description of Related Art
Conventionally, as a frame structure of a vehicle seat, a structure that is configured by joining two metal frame members with different structural strength has been known (Japanese Patent Application Publication No. 2013-193586 (JP 2013-193586 A)). The frame structure is configured as a side frame of a seatback, and is configured such that a frame member with high strength is provided in a base side that is supported from a lower end side via a recliner and a frame member with lower strength is joined to an upper side of the frame member with high strength.
In the above related art, when a large load is applied to the seatback in a front-rear direction, and a large bending load around the recliner is applied to the side frame, stress concentration may occur in a portion where the two frame members are joined and the structural strength sharply changes. Meanwhile, in the case where the portion is reinforced by, for example, increasing the thickness of the portion, the weight increases.